1914) 
SCHRAMM—GRASS-GREEN ALG! AND ELEMENTARY NITROGEN 169 
explained the growth of the lupines by supposing that the soil 
bacteria fixed free nitrogen at the expense of energy-furnishing 
organic materials supplied by the alge, and that the nitrogen 
so fixed in organic form became available to the legumes. 
A return to the conclusion that members of the Cyanophycee 
fix free atmospherie nitrogen is found in an investigation by 
Beyerinck (2). From 1} to 2-liter portions of tap or distilled 
water containing 0.02 per cent dipotassium acid phosphate were 
inoculated with 1-2 grams of garden soil, and placed in the light. 
After several weeks a characteristic growth of blue-green alge 
developed, containing, among other species, Anabena catenula, a 
form related to or identical with Nostoc paludosum, and Nostoc 
sphericum,—all non-motile species of Cyanophyceew. The devel- 
opment of the blue-green alge іп an almost nitrogen-free medium 
led Beyerinck, without analytical data, and in spite of the evident 
contamination of his cultures with soil bacteria, to the con- 
clusion that the Cyanophycee belong to the class of organisms 
possessing the faculty of free-nitrogen fixation. He regards the 
Cyanophycee as the only known organisms capable of synthe- 
sizing their organie materials from carbon dioxide and free 
nitrogen, and considers as significant in this connection the 
observations of Graebner (13) and Treub (37), who found that 
in the sequence of floras on fresh sand and lava soils, species of 
Cyanophycee are the first to appear. 
Cystococcus humicola was once more subjected to a careful 
investigation by Charpentier (7). His previous experiments 
had demonstrated that the dry weight of algal growth obtained 
in liquid glucose media was about one-half that of the weight of 
glucose consumed, and that 5.14 per cent of this dry weight 
was nitrogen. He then pointed out that the quantity of nitro- 
gen furnished by Kossowitsch to his pure cultures of Cystococcus 
humicola in the form of potassium nitrate was sufficient to 
produce at least 40 milligrams of growth (dry weight), and that 
while this growth was being produced it might not be neces- 
sary for the alga to seek nitrogen from the atmosphere. Once 
the dextrose was exhausted, the alga might, it is true, develop at 
the expense of atmospheric carbon dioxide, but the author holds 
the opinion that this would mean a double expenditure of energy 
for the assimilation of both carbon dioxide and free nitrogen and 
